A battery assembly for hybrid, plug-in electric (EV), or other type vehicles includes a plurality of battery cells. Cooling fins, repeating frames and foams, and electrical interconnects are joined to the battery cells to form a battery module or battery pack. The battery module for a long driving range EV may contain more than two hundred battery cells.
Currently, after stacking and assembling the battery cells and other components into the battery module, every two or three adjacent battery cells are welded together with U-channel sheet metals to form serial/parallel electric connections. Specifically, each of the battery cells has at least two tabs or electric terminals (one positive, one negative) that are welded to the U-channel sheet metals. In certain applications, the tabs of each of the battery cells are bent such that the tips of the tabs are aligned after welding. Unfortunately, due to the difficulty of precise tab bending and position control during welding, uneven tab height still exists. Uneven and misaligned tabs affect the overall weld quality between the tabs and the U-channel sheets and pose a risk of short circuiting due to tab interference.
Furthermore, because of the irreversible nature of current welding techniques, such as spot welding and ultrasonic welding, removing a defective or “bad” battery cell from a fully assembled battery module requires cutting all of the tab connections in the battery module, thereby rendering the “good” battery cells unusable for re-weld or restoration to another battery module.
It would be desirable to develop a battery module and a method of assembling the battery module, wherein the battery module is repairable and remanufacturable at a minimal effort and cost, while maintaining a flexibility in serial/parallel connection of a plurality of battery cells as well as minimizing an occurrence of uneven tab alignment.